Adding LED's to ESD mat and wrist-strap grounding

[redwire]

I always have problems with bench ESD mats becoming ungrounded. The snap pops off, wires break, and the end is usually buried under a ton of stuff on the bench.

I put a pair of high-brightness 3V green LED's in series with the mat ground.
Getting up and moving my feet, while touching the ESD mat, one LED surges bright depending on static polarity.
This is kind of what I expect to happen while wearing no wrist-strap. Your body gets a triboelectric charge from friction with the chair, or moving your feet.

To my surprise, the LED's light up (dimly) all the time

I measure 3uA AC and amazed the green LED's indicate so low. About 70pF of stray capacitance between mat and mains cords to get this current.

You might want to add these indicators. It's great to know your mat is grounded or if leakage current is high.

The LED's are 100mA peak rated and I haven't hit them hard- winter I can easily make 20kV so we'll see if this lasts.

[stj]

Re: Adding LED's to ESD mat and wrist-strap grounding

put a neon in parallel
that will limit the led voltage so they only get destroyed by about 80v

[redwire]

Re: Adding LED's to ESD mat and wrist-strap grounding

The neon lamp I don't think can work on an ESD mat ground.

I was going to use one, then realized the 1 MEG safety resistor limits current to prevent lethal shock if you touch mains while grounded to the mat or a wrist-strap.

Bypassing the resistor+LED's with a neon lamp, then no current-limiting once it's lit. So you could get mains shock.


My multimeter will not read in the 50-100 MEG resistance of static-dissipative plastics.
These silly LED's also can be used to check out anti-static bags, foam etc., they don't light up through ordinary plastic.